The invention relates to expandable structures, which in use, are deployed in interior body regions of humans and other animals. More particularly, the present invention is directed to an apparatus and method for extending a balloon in an crushed vertebra by sequentially inflating a balloon in a groove director and filling the open chamber of the vertebrae with osteogenic material.
When cancellous bone becomes diseased for various reasons such as a result of osteoporosis, avascular necrosis, cancer or other diseases, the surrounding cortical bone becomes prone to compression fracture or collapse because the cancerous bone does not provide the necessary interior support for the surrounding cortical bone. The treatment of such collapsed or fractured bone has utilized a number of medical devices.
One type of medical devices used in the treatment of collapsed or fractured bone utilizes expandable structures to reconstitute the structure of the bone. The deployment of expandable structures into interior body regions for various medical purposes is well known in the medical art. For example, expandable structures, generically called xe2x80x9cballoons,xe2x80x9d are deployed during angioplasty to open occluded blood vessels. As another example, U.S. Pat. Nos. 4,969,888 and 5,108,404 disclose apparatus and methods the use of expandable structures for the fixation of fractures or other osteoporotic and non-osteoporotic conditions of human and animal bones.
U.S. Pat. No. 4,313,434 to Segal describes a method for fixation of fracture of long bones using a flexible, inflatable bladder inside the intramedullar cavity. A small opening is drilled in the bone, and the bladder is inserted through the hole into the intramedullar cavity. The bladder is then inflated with sterile air and sealed, to fixate the bone. After the fracture has healed, the bladder is deflated and removed.
U.S. Pat. Nos. 5,423,850 and 5,480,400 both to Berger, the inventor of the present application, describe methods and devices of bone fixation using a balloon catheter. The catheter, with the deflated balloon at its distal end, is inserted into the intramedullar cavity, past the fracture site. In the ""850 patent, the balloon is inserted by guiding it along guide wires that are fed through the cavity, before introducing the catheter. Once fully inserted in the cavity, the balloon is inflated to anchor it in place, and the catheter is tightened against the balloon to provide compression to the fracture.
These patents provide only a joining effect as in the pulling of one broken bone towards the other.
Various medical apparatus currently used, include balloon expandable devices where an expandable balloon is used to change the shape of an implant or a collapsed or fracture vertebrae. Such balloon devices use hydraulic pressure by the insertion of fluid into the balloon""s interior, thereby enlarging the balloon""s diameter. The pressure of the fluid within the sealed balloon provides the energy to support the balloon in its expanded shape. These types of vertebral balloons inflate spherically in all directions and it is difficult to guide and control the force of expansion in the vertebrae resulting in uneven application of force with portions of a crushed vertebra not being expanded to the original configuration.
U.S. Pat. No. 5,972,015 is directed toward a device intended for deployment into interior body regions employing a catheter tube which carries an expandable structure. The structure can include spaced apart end regions which provide a non-conical diameter transition between the diameter of the catheter tube and the larger diameter of the expanded structure. The non-conical diameter transition mitigates the tradeoff, present in other balloon structures between achieving a desired maximum expanded diameter without undesired reduction in the effective length of the structure.
U.S. Pat. No. 6,241,734 discloses a system and method for delivering material into a bone deploying a cannula through soft tissue to establish a subcutaneous path into the bone. A material is introduced into the bone through the cannula. The apparatus and method advance a tamping instrument having a body including markings located along the length in increments from the terminus which allow the physician to gauge the position of the instrument in the subcutaneous path as material is being tamped into the bone. The tamping instrument is deployed through the cannula to urge material residing in the cannula into the bone and deliver a material at a pressure which is no greater no greater than about 360 psi.
U.S. Pat. No. 6,248,110 is a system and method for treating fractured or diseased bone by deploying several therapeutic tools into the bone. An expandable balloon body is deployed in association with a bone cement nozzle into the bone such that both occupy the bone interior at the same time. Expansion of the balloon body forms cavities in the cancerous bone in the interior bone volume.
It is important to maximize the size and surface area of an expandable structure when deployed in an interior body region. Current medical balloons manufactured by molding techniques are designed to be guided into a narrow channel, such as a blood vessel or the fallopian tube, where they are then inflated. In this environment, the diameter of the balloon is critical to its success, but the length is less so. Such balloons only need to be long enough to cross the area of intended use, with few constraints past the effective portion of the inflated balloon. This allows conventional balloons to be constructed in three molded pieces, comprising a cylindrical middle section and two conical ends, bonded to a catheter shaft. As a practical matter, neither the length of the conical end, nor the length of the bond of the balloon to the catheter shaft, affect the function of conventional balloons, and these regions on conventional balloons are often 1 cm in length or more. Indeed, the larger the balloon diameter, the longer the end cone, which creates a tradeoff between maximum effective length and maximum effective diameter. This tradeoff makes optimization of conventional structures problematic in interior structures with defined lengths, such as bone.
Vertebroplasty is a recent surgical technique which uses the injection of a cement material into a collapsing vertebral body. Osteoporosis is the leading cause of vertebral fracture. Approximately 700,00 vertebral fractures occur annually in the United States. The procedure is performed to reinforce the fractured bone, alleviate chronic back and prevent further vertebral collapse. Vertebroplasty was developed in France in the 1980""s but is relatively new in the United States and is presently available in only a few hospitals.
Deramond et al., xe2x80x9cPercutaneous vertebroplasty with methyl-methacrylate: technique, method, results [abstract].xe2x80x9d Radiology 1990;117 (suppl):352; among others, have described the percutaneous injection of PMMA into vertebral compression fractures by the transpedicular or paravertebral approach under CT and/or fluoroscopic guidance. Percutaneous vertebroplasty is desirable from the standpoint that it is minimally invasive, compared to the alternative of surgically exposing the hard tissue site to be supplemented with PMMA or other filler.
The general procedure for performing percutaneous vertebroplasty includes the percutaneous injection of PMMA or other bone implant material into the damaged or fractured bone tissue of a vertebra. During injection of the bone implant material, fluoroscopic imaging or another imaging technique is used to track the path that the bone implant material takes as well as its final position upon implantation. Contrast agents such as barium sulfate powder are often used to aid the visibility of the bone implant material by imaging. This type of contrast agent is fairly effective once a given mass of the mixture of it with the bone implant material has accumulated at an implant site. However, for purposes of tracking the flow and leading edge surfaces of a bone implant material during injection, or for viewing small volumes of the implant material, the contrast agents presently used are adequate.
As an adjunct to the balloon devices, a material which solidifies (e.g. by polymerization) is inserted into a balloon, forming a solid which has a new shape. This material can have two-component cement properties, and can be formed of epoxy or polymer. The material is compressed into the balloon and solidifies by change in temperature or humidity.
One aspect of the invention provides a device for deployment into an interior body region comprising a grooved director tube, which carries an expandable structure. The structure preferably a balloon is adapted to assume a collapsed geometry for deployment into the vertebra and an expanded geometry for use within the vertebra. The grooved director extends along a first axis and the geometry of the balloon extends outward from that axis against the vertebra walls restoring the same to their original configuration. This permits sequential deployment of the balloon in a symmetric fashion with respect to the natural axis of a targeted interior body region, even when the groove director is not aligned with the natural axis.
After the vertebra walls have been expanded by the balloon, a slurry or paste of biocompatible filler material is placed inside the vertebra. The hard tissue implant material may be mixed with the radiopaque particles and include hydroxy apatite, various formulations of biocompatible calcium phosphates, biocompatible calcium sulfates, demineralized and/or mineralized bone particles, polymer based implants including polyglycolic acid and/or polylactic acid compounds, collagen and/or collagen derivative preparations alone or in combination with other biomaterials, chitin and/or chitosan preparations, bioglasses including oxides of silicon, sodium, calcium and phosphorous and combinations thereof, and other known materials which are acceptable for use as hard tissue implant materials including osteogenic and osteoinductive compositions, and combinations thereof.
It is an object of the present invention to provide a device which is able to guide, concentrate, control and improve the force of balloon compression in a collapsed vertebral body.
It is another object of the invention to provide a device which can be rotated in the vertebral body to provide selected areas of force against cancerous bone and cortical bone of the vertebral body.
It is yet another object of the invention to provide a device to deliver bone graft material or cement into a vertebral body after expansion of same.
In the accompanying drawings, there is shown an illustrative embodiment of the invention from which these and other objectives, novel features and advantages will be readily apparent.